Process for the production of cast iron



July 3, 1934. I 1,965,436

- PROCESS FOR THE PRODUCTION OF CAST IRON Filed March 31, 1931 3.2 as M %CARB0N Z2 2.3 2.4 2.5 2,6 2.7 25 CARBON /A THE G/MIRGE IN VEN TOR.

BY fiOmu/m A TTORNEYS.

,6 CARBON Patented July 3, 1934 PATENT OFFICE PROCESS FOR THE PRODUCTION or" CAST IRON Karl Sipp, Mannheim, Germany, assignor to Heinrich Lanz Aktiengesellschaft, Mannheim,

Germany Application March 31,

1931, Serial No. 526,597

In Germany April 23, 1930 Claims.

This invention relates to the production of cast iron, and, more particularly, to the production of cast iron of specific quality in cupola furnaces; and it consists in the control of the carbon 5 content in cupola furnace operation in order to adjust the same to the silicon and manganese contents of iron of the quality desired in each .individual case.

The quality of cast iron depends, aside from certain manufacturing processes, primarily on its chemical composition, 1. e., on its constituents in carbon, silicon, manganese, phosphorus and sulfur. For a cast iron possessing good mechanical and physical qualities, the phosphorus as possible, and this can -be.done by the calculation of the mixture of the charge, the quality of the coke used, and certain additions such as fluxes. The respective influences of the carbon, silicon and manganese have a certain relation one to another-for instance, one can produce mechanically equivalent cast iron with a low carbon and higher silicon content or a higher carbon and a low silicon content or a high manganese content with higher carbon and silicon contents and vice versa. The silicon content and the mam ganese content can also be controlled after the iron flows, for example, by the addition of ferrosilicon or ferro-manganese. But thecarbon content can hardly be influenced at this late stage; and up to the present time no way has been found to control, in a dependable way, the carbon con-- tent of the iron in cupola furnace operation. In

particular, the research work heretofore carried j out in this connection has not disclosed the influence of the combustibility, i. e., the reaction temperature, of the coke used on the obtaining of specific carbon contents in the cast iron.

My invention is based on the discovery of the has a constant relation to the calculation of the mixture of the charge and so affords a dependable guide for obtaining a specific carbon content in the cast iron. And: following up thisdiscovery I have worked out a series of graphs based on the ascertained relationship between the reaction and sulfur contents are usually kept down asv low fact that the reaction temperature of the coke kinds of coke used therewith is shown by way of illustration in the accompanying drawing, wherein the heavy full line a refers to a coke which burns with difliculty, having a reaction temperature of 750, the light dash line b refers to a coke having a reaction temperature of 725, the dot and dash line-c refers to a coke having a reaction temperature of 700, the light full line at refers to a coke having a reaction temperature of 675, and the light dash line e refers to a coke having a reaction temperature of 650. The abscissas indicate the calculated carbon content of the mixture charged, while the ordinates indicate the carbon content of the cast iron produced.

Referring to-the diagram it will be noted that, for any given calculation of the mixture charged, the carbon content in the analyses increases as the reaction temperature of the coke used decreases. Hence, following the diagram, it is possible to obtain the desired carbon content in the analyses eitherwith a coke'cf specific reaction temperature from a suitably calculated mixture, or from a specifically calculated mixture'by using a coke having a reaction temperaturesultably coordinated thereto'.

Of course, in cupola'furnace operation other factors also play a 'partfor instance, the mannerof ,the'introdu'ction of the blast of combustion ,air. Ihelgr'aphs of the drawing refer to a cupola furnace with double rows of tuyeres which 'are 'l00 millimeters distant from each other. If the admission of the blast ischanged by closing "the upper-row of tuyeres, a drop of 0.2 per cent. of the carbon content in the analyses will result and such drop should be deducted from the percentages given in the diagram. For example, the carbon content of the analyses given as 3.00 per cent. in the diagram will be 2.8 per cent. when only one row of tuyeres is used Otherwise, the curved lines remain the same as shown in the diagram. 7

Since as already indicated the silicon and/or manganese content of the charges influences the quality of the iron cast 'therefrom, the values of the percentages therein given for the carbon content in the analyses will be raised or lowered somewhat by variations in the amount of these elements contained in the charges. The general character of the graphs, however, remains substantially the same. I

For the actual practice of my new process in a given cupola furnace, therefore, three melts should be poured with the mixtures usually used, changing only the kind of coke and using for the melts cokes of reaction temperatures correspondin the drawing. Analyses of the melts should then be made and the percentages of their carbon content noted and the values given therefor on the illustrative diagram revised up or down accordingly. It may also be found advantageous-to pour one or two more series of melts using in each series the same three different kinds of coke as before .but modifying the mixture charged, and to register the percentages of ,the carbon in the analyses. The foundryman, having thus ascertained and noted the, operative effects in his cupola of the different kinds of coke on the mixtures charged, is at all times thereafter in a position, by following the admixture diagram with its values of the carbon content in the analyses thus revised, to so co-ordinate the carbon content of his mixture with the reaction temperatures of the coke as to obtain with precision any predetermined carbon content in his castings.

Hence, according to my invention, it is possible to accurately control the carbon content relative to the silicon and manganese contents of cast iron produced for special uses by suitably coordinating the calculation of the mixture and the specific reaction temperature of the coke in accordance with the constant relationship between the two as determined by the ascertained operative characteristics of the individual furnace.

The centigrade temperature scale is used throughout the specification and in the appended claims.

What I claim as new, and desire to secure by Letters Patent, is-

1. The process of producing cast iron of specific quality in a cupola furnace by the use of coke of different reaction temperatures which comprises the step of controlling the carbon content thereof by adjusting one to the other the calculated carbon content of the mixture of the charge and the reaction temperature of the coke used in accordance with the constant relationship between them, namely, that with any given carbon content in the specific mixture charged cokes of definitely higher reaction temperatures will give definitely smaller increases in the carbon content of the melt and vice versa.

2. The process of producing cast iron of specific quality in {a cupola furnace which comprises the step of controlling the carbon content thereof by using with any calculated mixture of the charge a coke of the reaction temperature indiing to three of the five for which graphs are given cated as adapted to effect the definite increase of carbon content required by graphs based on the ascertained constant relationship between the reaction temperature of the coke and the calculation of the mixture of the charge, whereby with any given carbon content in the specific mixture charged cokes of definitely higher reaction temperatures will give definitely smaller increases in the carbon content of the melt and vice versa.

3. The process of producing cast iron of specific quality in a cupola furnace which comprises the step of controlling the carbon content thereof by adjusting one to the other the reaction temperature of the coke used and the calculation of the mixture of the charge in accordance with the constant relationship between the two, namely, that with any given carbon content in the mixture charged cokes of definitely higher reaction temperatures will give definitely smaller increases in the carbon"-contentof the melt and vice versa, and with the specific values of such increase indicated by the ascertained efiect thereon of the operative characteristics of the individual cupola furnace.

4. The process of producing cast iron of specific quality in a cupola furnace which comprises the steps of ascertaining the operative effects in a given cupola furnace of cokes of different reaction temperatures on the mixtures charged and thereafter controlling the carbon content of the melts made therein by adjusting one to the other the calculated carbon content of the mixture charged and the reaction temperature of the coke used in substantial accordance with typical graphs based on the constant relationship between the two and having, substituted for the values of the carbon content in the analyses thereon given, the specific values of the carbon content in the analyses obtained from trial melts in the individual cupola furnace.

5. The process of producing cast iron of specific quality in a cupola furnace by the use of .coke of different reaction temperatures which comprise s ,,the stepmf controlling the carbon content thereof by adjusting one to the other the calculated carbon content of the mixture of the charge and the reaction temperature of the coke used in accordance with the definite and constant 

